Molecular Clouds in the Second Quadrant of the Milky Way Midplane from l = 104.°75 to l = 119.°75 and b = −5.°25 to b = 5.°25

Abstract

Abstract In this work, we study the properties of molecular clouds in the second quadrant of the Milky Way Midplane, from l = 104.°75 to l = 119.°75, and b = −5.°25 to b = 5.°25, using the 12CO, 13CO, and C18O J = 1 − 0 emission line data from the Milky Way Imaging Scroll Painting project. We identify 857 and 300 clouds in the 12CO and 13CO spectral cubes, respectively, using the DENDROGRAM + SCIMES algorithms. The distances of the molecular clouds are estimated, and physical properties such as the mass, size, and surface densities of the clouds are tabulated. The molecular clouds in the Perseus Arm are about 30−50 times more massive, and 4−6 times larger than the clouds in the Local Arm. This result, however, is likely to be biased by distance selection effects. The surface densities of the clouds are enhanced in the Perseus Arm, with an average value of ∼100 M ⊙ pc−2. Here. we select the 40 most extended (>0.35 arcdeg2) molecular clouds from the 12CO catalog to build the H2 column density probability distribution function (N-PDF). Some 78% of the N-PDFs of the selected molecular clouds are well fitted with log-normal functions with only small deviations at high densities, corresponding to star-forming regions with scales of ∼1–5 pc in the Local Arm, and ∼5–10 pc in the Perseus Arm. About 18% of the selected molecular clouds have power-law N-PDFs at high densities. In these molecular clouds, the majority of the regions fitted with the power law correspond to molecular clumps at sizes of ∼1 pc, or filaments at widths of ∼1 pc.